Compensating device



* Aug. 13, 1929.

ESS aEIS I' W M. KNIGHT 1,724,405

CMPENSATING. DEVICE Filed Oct. 3, 1925 UBY AT'ToRNEY Patented Aug. 13, 1929.

UNITED STATES PATENT OFFICE.

MONTGOMERY KNIGHT, 0F HOLYOKE, MASSACHUSETTS, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

COMPENSATING DEVICE.

Application led October 3, 1925.

My invention relates to compensating means for electroresponsive devices, and particularly to means for compensating electric meters or fiuX-producing elements for the effects of' varying conditions, such as temperature changes, thereon.

One object of my invention is to provide a compensating device, of the above-indi.- cated character, that shall be simple and durable in construction, economical to manufacture and effective in its operation.

Another object of my invention is to provide a compensating device that shall be readily adapted for co-operation with a standard structure Without material change in the latter.

Another object of my invention is to provide a temperature compensating device that shall retain its characteristics as initially calibrated.

Another object of my invention is to provide Aa flux-producing compensating device Vtor co-operation with finir-producing elements, in contradistinction to the man v forms of devices Which only modify the fluxes to be compensated but do not produce fiuxes.

A further object of my invention is to provide a temperature-responsive compensatingl device that shall comprise differentially-related elements of such temperature coeflicients that the element With Which they are co-operating under given conditions is unaffected but that shall compensate the flux of the element in accordance with variations from said conditions.

lVith such objects in view, as Well as other advantages which may be incident to the utilization of the improvement, the invention consists in the parts and combinations thereof hereinafter set forth and claimed, With the understanding that the several necessary elements constituting the same may be varied in proportion and arrangement ivithout departing from the nature and scope of the invention.

In the prior art, Watthour metersv and other devices employing electromagnetic fluxes as essential elements of their operation have been subject to serious errors caused by temperature changes and other variable conditions.

Many suggestions for the correction of such errors have been made lmost of which are impracticable for various reasons, one

Serial No. 60,291.

being that certain of the Suggestions require radical and expensive changes in the devices with which they are adapted to co-operate. One suggestion, Which has been advanced in a Wide variety of forms, calls for the use of a movable keeper for the meter magnets to be moved by a temperature-responsivc bimetallic element. relatively cumbersome and only adaptable for its purpose with the exercise oiE extreme care and skill. This is because of the size of the bimetallic element required to obtain suflicient movement ofl the keeper and the usually limited space for such a device in meters of standard practice.

Other suggestions have been made which are not subject to the above-mentionety objection, but all of them, to the best of my knowledge, only modify the flux they are to compensate and do not produce a variabie flux to positively aid or oppose the compensated flux as by my invention.

A further objection to certain of the prior art devices is that they do not sufficiently retain their original characteristics, as in the fatigue of the bimetallic elements.-

It is my aim to provide means for compensating for variable conditions in a fluxresponsive device by positively aiding and opposing the operating flux, in contradistinction to merely modifying it, and to pro- -vide a device that shall not only retain its initially-calibrated characteristics but that may be added to a standard structure Without material change therein.

Accordingly, in practicing my invent-ion, I provide co-operating flux-producing elements that are so differentially related to each other and to the de y'ice to be compensated and that are constructed to be of such different characteristics as not to affect the device under given conditions, but that shall positively aid or oppose t-he flux of the device in accordance vvith the extent and direction of variation from saidfconditions.

Figure l of the accompanying drawings is a diagrammatic vieu7 of a device embodying my invention;

Fig. 2 is a diagram of the device of my invention, as applied to a Watthour meter;

Fig. 3 is a diagram, in simplified form of the device of Fig. 2, With certain parts omitted; and

Fig. 4 is a vieW similar to Fig. 3 of a modified form of my invention.

Such device is usually'l In one of its simplified forins,-as shown in Fig. 1, ythe device comprises a main fluxproducing winding 1, such as one of the operating windings of a watthour meter. In this instance, the winding 1 represents the series winding or windings of a watthour meter of usual type.

Connected in series relation to the winding 1 are a pair of parallel-connected coils 2 and 3 of materials, such as copper and advance, respectively, that are differentially wound and otherwise so constructed and related to eachJ other as to produce .equal and opposite fluxes under given temperature conditions.

The fluxes of the coils 2 and 3 are so vrelated to the main operating flux of the winding 1 that, at said given temperature, they have no effect thereon but that, with a rise or `fall of temperature, they become unbalanced to yproduce a result-ant flux. This resultant flux iay be adapted to Veither aid oroppose the flux to be compensated in one direction from said given temperature and to respectively oppose or aid tlie fluX in the opposite direction as desired.

The adaptation of the above-described suggestion to a watthour meter of standard `form is illustrated :more clearly in Fig. 2, in which a laminated core structure 5, a

`shunt or voltage winding 6, a series winding or windings 8-9, corresponding to the winding vl of Fig. 1, and a lag plate 10 are constructed and related in a usual manner but augmented by coils 11-14 and 12-15, corresponding to the coils 2 and 3 of Fig. 1.

The core structure 5 is of a usual form comprising a main central leg orpole por- ,tion 16 around which .the voltage coil 6 is disposed and which is divided at its outer or lower end into two smaller portions 17. These portions are paired with similar por- Y tions 18 projecting from the sides 19 of the v,and 12, While the other is surrounded. by the -coilsA 9, 14: and 15.

A disc armature 21, mounted on a shaft 22, is disposed in an air gap 23 between the pole portions 17-18, at one side thereof, .and a bottom or cross portion 241 of the magnet structure 5, at the other side, and is adapted for actuating an indicating member or meter register (not shown) in a usual and wellknown manner.

coils Sand 9, with the fluxes thereof in opposite directions, as indicated by the arrows so that, when augmented by the flux from Athe voltage coil, quadrature-related fluxes sultant flux will be produced, as in the form of device shown in Fig. 1, to augment or oppose the ordinary fluxes of `the meter in one direction from theV given temperature and to Voppositely affect the meter fluxes in the opposite direction.

This action will be apparent from a study of the arrows in Fig. .3, in which the fluxes of the coils 11 and 12 normally cancel or nullify each other as do the fluxes of the coils 14 and 15, thus leaving, at said given or )redetermined tem jerature onl the ef-A feet of the fluxes yin the coils l8 and V9l as modified by the fluxproduced by the voltage coil 6.

The fluxes from the coils 8, 9 and 6 are ordinarily affected Vby temperature changes to cause the meter to operatefinaccurately. However, in the device of my invention,

.this change is opposed substantially iin accordance with its extent by the coils 11, 12,

V14 and 15 to cause the meter to operate more accurately over a relatively wide'range of temperature change.

By properly 4:proportioning ythe compensating coils and the lag plate lO'both as to lrelative magnitude and temperature coeflicients, complete compensation for temperature changes of all power factors may be effected. Y

rlhus'by the simple expedient set forth, a standard watthour meter or other device may be quickly and economically compensated for errors incident to temperature changes without-.materially .altering its conf struction.

ln the Vmodification of my invention shown in Fig. fl, in whichV corresponding parts are designated by corresponding reference characters, the construction and operation are similar except that a variable'reactor 26 is substituted for the lag plate 1() in the branch of the parallel compensating circuit in which the low-temperature-coefficient coils 12 and 15 are disposed.

In this construction, in which temperature compensation is also effected for` inductive loads at all power factors, the lagging, instemLL of being effected by the lag plate 10,

las inthe form of my invention shown in Figs. 2 and 3, is effected by the reactor 26 in the low-temperature-coeflicient circuit.

In accordance with the provisions of the pat-ent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but

I desire to have it understood that the apparatus shown and described is only illustrative and that the invention may be carried out by other means.

I claim as my invention:

1. The combination with a flux-producing winding, of a pair of coils connected in parallel to each other, the parallel circuit formed by the coils being connected in series relation to said winding and adapted at a given temperature to produce equal and opposite fluxes, said coils being constructed of' materials having different temperature coefficients and the fluxes thereof being related to the flux of the winding to compensate the same for temperature variations from sait given temperature.

2. The combination with a pair of oppositely-wound, series related, flux-producing windings, of a parallel circuit connected in series with said windings comprising two branches each including a coil disposed coaXially with one of said windings, said parallel circuit being normally inoperative to produce flux under a given temperature condition, but effective to aid or oppose the fluxes of said windings in accordance with variations from said condition.

The combination with a pair of oppositely-wound, series-related, flux-producing windings, of a parallel circuit connected in series with said windings, comprising a plurality of branches, each of said branches including a plurality of oppositely wound coils, said branches comprising different temperature coefficients, a certain coil of cach of said branches being disposed coaxially with one of said windings.

4. In an induction meter, the combination with a magnetizable core member and actuating windings thereon, of means for compensating the meter for temperature variations comprising coils connected in differential parallel relation, said coils being adapted for normally producing eqnal and opposite fluxes unser given temperature conditions but having different temperature coe'lhcients and related to the windings to aid or oppose the winding fluxes in accordance with variations fromsaid given temperature conditions.

5, In an alternating-current instrument, the combination with means for producing actuating and controlling fluxes, of means comprising flux-producing structure for causing a predetermined phase displacement between the actuating fluxes of the meter at a given power factor and for producing normally equal and opposite fluxes at a given temperature which become unbalanced to produce flux to compensate said first fluxprodncing means for a change in iiuX mag-` nitude and phase displacement caused by temperature change.

In testimony whereof, I have hereunto subscribed my name this 30th day of September, 1925.

MONTGOMERY KNIGHT. 

